Tanium Client concepts

Registration

When you first deploy the Tanium Client to an endpoint, the client initiates a connection to Tanium™ as a Service (TaaS) the Tanium Server or Tanium Zone Server that is assigned to it in the initial configuration. During initial registration, the Tanium Client establishes a unique ID, and TaaS the server sends it the latest client settings, a list of nearby peers, and the latest definitions for sensors, questions, and scheduled actions. By default, the initial registration status is configured to reset at randomized intervals of two to six hours, forcing the Tanium Client to re-initialize registration. Repeating the initial registration ensures that TaaS the server applies the latest settings and the clients select optimal peers.

The Tanium Client also re-registers with TaaS the server through a normal registration, which occurs by default at a randomized interval of 30 to 90 seconds. During a normal registration, the Tanium Client reports its current state of questions, actions, and settings to TaaS the server. In response, TaaS the server sends new questions, actions, or settings to apply. In environments with numerous endpoints, normal registrations are the primary way that Tanium Clients receive new questions, actions, and settings.

Client peering

In an enterprise network, Tanium Clients establish peer relationships with each other in a linear chain. Peer connections are continuous, long-lived connections that the clients use to exchange Tanium messages and files. During registration, TaaS the server sends the Tanium Client a peer list of other Tanium Clients with which it can try to establish a peer connection. The Tanium Client uses the list to determine which peers are the most optimal neighbors within the linear chain.

To customize client peering settings to suit your deployment, see Configuring Tanium Client peering.

Forward and backward leaders

By design, one forward leader and one backward leader terminate opposite ends of the linear chain. Other than at registration, only leaders establish direct connections with TaaS the Tanium Server or Zone Server. TaaS The server passes sensors, questions, and scheduled actions to the backward leader, which passes them to its forward peer, which in turn passes them to its forward peer, and so on, until they reach the forward leader. The forward leader returns the question answers and the scheduled action statuses to TaaS the server.

Tanium Clients establish outgoing connections to backward peers for file distribution (see File distribution).

Figure  1:  Tanium Client linear chain

Forward and backward reflection

Tanium peer communication is designed to accommodate new clients that come online, to route around clients that are removed or stop communicating effectively, and to reflect around network-level blockages, such as firewall blocking. Forward reflection occurs if a Tanium Client cannot establish an outgoing connection to a forward peer in its peer list: the client establishes its forward connection to TaaS the server instead and becomes a forward leader. Similarly, backward reflection occurs if a Tanium Client cannot establish an outgoing connection to a backward peer: the client establishes a backward connection to TaaS the server and becomes a backward leader.

LAN and WAN connections

Client peering results in a profound reduction in connections and bandwidth over WAN links. The following figure illustrates the proportions of the savings in a large enterprise network that has subnets in a data center, headquarters, and branch office, as well as VPN connections from remote workers. Other than during registration, only the remote VPN clients and leaders, depicted in bright red, connect to TaaS the server over the WAN (the internet, in this example). The remaining clients, depicted in darker red, share data over peer connections on the LAN for each subnet.

Figure  2:  Client peering in an enterprise network

Satellites

Satellites are specific Tanium Clients that you designate to run certain targeted, secure workloads on behalf of the Module Server,TaaS, such as non-line-of-sight scans in Discover or remote authenticated scans in Comply.

Figure  3:  Tanium Client designated as a satellite

For example, suppose you have a lab network with unmanaged endpoints on a subnet separated from your main network, and you want to use Comply to perform scans on the lab endpoints. Also suppose you are using a managed endpoint with multiple network interface controllers (NICs) to bridge the lab subnet to the main network. You can designate that endpoint as a satellite and then configure Comply to use it to perform scans on the unmanaged endpoints.

Because the server TaaS might need to send sensitive, encrypted data (such as credentials) to a satellite when running a workload, you must verify each endpoint that you designate as a satellite to prevent spoofing attacks. Any such sensitive data is never sent using the linear chain, nor is it stored on disk on the satellite.

Designating and using satellites requires Direct Connect version 2.1 or later.

For more information about managing satellites, see Tanium Direct Connect User Guide: Managing satellites.

File distribution

TaaS The Tanium Server distributes files (through a Zone Server, if one is deployed) to managed endpoints when you deploy actions that use those files. For example, if you deploy an action to upgrade Windows, TaaS the Tanium Server distributes a package that includes the Windows patch file. Tanium Clients running on the endpoints optimize the file distribution process through peering and caching.

File distribution among peers

Peering reduces the number of files that TaaS the Tanium Server distributes over WAN links. Instead of sending files to all managed endpoints, TaaS the Tanium Server sends files only to the backward leader of each linear chain. Each backward leader then relays the files over a high-speed LAN connection from one forward peer to another until they reach the forward leader.

Shard caching

Caching enables clients to redistribute files in small chunks known as shards. Each client maintains an intelligent local cache of the shard files that TaaS the Tanium Server previously distributed to the linear chain. When the same files are requested later (for example, when an action runs again), clients can reassemble the files by collecting shards from their peers over the LAN, rather than requesting that TaaS the Tanium Server redistribute the files again. By default, each client maintains a shard cache of 100 MB. Each client keeps particular shards based on an algorithm to ensure an efficient distribution. These caches are also self-cleaning based on an algorithm that prioritizes recently used shards.

To distribute a file, TaaS the Tanium Server first downloads it and divides it into multiple shard files. Each shard is associated with a hash value. TaaSThe Tanium Server then creates a manifest that maps all the component shards to the entire file. When you use TaaS the Tanium Server to distribute a package that includes a file, the package includes the manifest for that file.

TaaS The Tanium Server does not deliver shards through the registration process as it does for questions and actions. Instead, TaaS the server delivers shards to each linear chain through the backward leader. When a Tanium Client receives the package and associated manifest file, it first checks its own cache to see if it already has any of the shards listed in the manifest. The Tanium Client then generates a new request message for all the shards that it could not find locally. This request message first flows forward along the linear chain to its end. As the request message traverses the chain, each peer checks its local cache for the listed shards. If the peer has one of the requested shards, it sends that shard to the requesting peer. To avoid duplication, it also removes that particular entry from the request message before propagating the message to the next peer in the chain. If Tanium Clients do not find all the shards after the forward flow along the chain, the clients send a request for shards that traverses the chain in the reverse direction. If shards are still missing after each peer has investigated its cache, the first Tanium Client requests the missing shards directly from TaaS the Tanium Server and distributes them appropriately.

Figure  4:  Tanium shard files

TLS

TaaS Tanium Core Platform 7.2 or later supports Transport Layer Security (TLS) for encrypted communication in connections from Tanium Clients to TaaS the Tanium Server or Zone Server. Tanium Client 7.4 or later uses TLS communication by default between client peers. For details, see the Tanium Core Platform Deployment Reference Guide: Setting up TLS communication.